Air-conditioning system for cooling or heating



Oct. 14, 1947. R. R. HAWKINS AIR CONDITIONING SYSTEM FOR COOLING 0R HEATING Filed July 10, 1944 4 Sheets-Sheet 1 Oct. 14, 1947. R. R. HAWKINS 2,428,375

AIR CONDITIONING SYSTEM FOR COOLING OR HEATING Filed July 10, 1944 4 Sheets-Sheet 2 I N VEN TOR.

Oct. 14, 1947. I R. R. HAWKINS 2,423,876

AIR CONDITIONING SYSTEM FOR COOLING OR Filed July 10, 1944 HEATING 4 Sheets-Sheet 3 Oct. 14, 1947. R. R. HAWKINS 2,428,876

AIR CONDITIONING SYSTEM FOR COOLING 0R HEATING 4 Sheets-Sheet 4 Filed July 10. 1944 INVENTOR.

WKAQW ATTORNEY.

-' 'from which heat Patented Oct. 14, 1947 AIR-CONDITIONING SYSTEM FOR COOLING OR HEATING Reginald R. Hawkins, Tuckahoe, N. Y.

Application July 10, l

8 Claims.

This invention relates to new and useful improvements in heating and, or, air-conditioning systems, and apparatus employed therein. It is especially adapted, but is not limited to, the type of such system that may be used either for heating or cooling, which type is generally known as the reverse-cycle refrigeration, or reverse-cycle air-conditioning type. The main feature of the invention is the provision in such systems of a special type of reservoir containing water or other suitable liquid and adapted to store considerable quantities of heat for use when the system is operating to heat the thing or space it is designed to heat and to absorb and dissipate considerable quantities of heat when the system is operating to cool the space or thing it is designed to cool.

One object of the invention is to provide a reservoir containing water or other suitable liquid, from which useful quantities of heat may be obtained by cooling the liquid, even to the extent of freezing it.

.A further object of the invention is to provide an efficient and economical means for warming and thawing the frozen liquid in the reservoir.

A still further object is to provide a reservoir containing water or other suitable liquid, adapted I to absorb considerable quantities of heat when the system of which it is a part is operating as a cooling system.

Yet a further object of the invention is to pro vide means for economically and automatically regulating the temperature of the reservoir including its contained liquid so that it will function as desired when the system of which it is a part is operating to heat, and, .or, when it is operating to cool.

Another object of the invention is to provide a form of reservoir into which heat will be conducted readily from the surrounding soil when the-temperature of the liquid within the reservoir falls below the temperature of the soil and, or, will be readily conducted into the surrounding soil when the temperature of the liquid in the reservoir rises above the temperature of the soil.

A further object of the invention is to provide a reservoir of the type described, the liquid which remains in the reservoir and does not cit culate in the refrigeration units and tubing of the heating and, or, cooling system.

Yet another object ofthe invention is to provide a form of reservoir in which the radiation of the sun may be utilized to add heat to the reservoir.

944, Serial No. 544,267

' ways and means whereby tween the upper as an absorber of heat when Further and more specific objects, features, and advantages will more clearly appear from a consideration of the following specification especially when taken in connection with the accompanying drawings which form part of the specification and which illustrate present preferred forms which the invention may assume.

It is believed desirable first to describe the drawings and then to describe the preferred forms shown in the drawings to acquaint the reader with what has been constructed to solve the problems, and thereafter to state the problems and they have been solved to meet the various conditions and requirements encountered in practical systems.

In the drawings, therefore,

Fig. l is a vertical cross section through the improved reservoir of a'form to be used beneath the cellar of a building;

Fig. 2 is a plan view thereof.

, Fig. 3 is a vertical cross section of a similar reservoir modified to take advantage of the heat of the sun;

Fig. 4 is a somewhat diagrammatic representation of the piping and related connections betank coil and the main conditioning system.

Fig. 5 is a similar view showing the connections between the lower tank coil and an outdoor radiating and, or, absorbing surface;

Fig, 6 is an electric circuit diagram for the system when it is designed for both heatingv and cooling under automatic thermostatic control and when the lower tank coil is part of a reverse-cycle system which employs outdoor air as a source of heat when the tank contents must be heated and the tank contents must be cooled; and

Fig. '7 is a circuit diagram showing the electric and piping connections for the right hand, or lower tank coil side of Fig. 6, when the lower coil is connected to an outside spring or water main.

One of the basic features of the invention concerns a reservoir shown in Figs. 1 and 2, in the form of a tank ill with walls of concrete or other suitable material which is sunk into the soil H and, in the form shown in these figures, is supposed to be disposed beneath the cellar floor l2 of a building, Preferably in this case, a manhole cover I3 is provided to permit from the cellar. At 1541' is shown a tube or container of metal or other suitable material adapted to support a'thermostat in thermal contact with the contents of the tank.

In order to permit the reservoir to absorb adaccess to the tank' ditional heat from the surrounding soil or to dissipate heat thereto depending upon whether the system is working on a heating or a cooling cycle, the tank I is provided with heat conductors I4 in the form of metal or other suitable material, preferably as rods which may be embedded in the tank wall or may terminate adjacent to the walls or may extend therethrough to the interior surface thereof as may be desired. These conductors enabl the heat of the surrounding soil to be conducted into the liquid of the tank and also permit the heat of the tank liquid to be conducted to the surrounding soil in reverse cycle operation.

Disposed in the tank III are two coils I5 and I 6 respectively at the bottom and top of the tank. These coils are connected outside the tank to suitable apparatus as will be later described. The

lower coil I5 is supported on or near the bottom of the tank and the upper coil I6 is positioned near the top of the tank, preferably on cross bars I1 as shown. The upper and lower coils are connected by heat-conducting elements I8. f

In the form of tank shown in Fig. 3, the tank is of the same general type as that shown in the previous figures but the top is open, or at least not covered beneath the cellar floor, and may have a half roof I9 with another half roof 20 of double-paned or heat-insulated glass directed toward the point of maximum average solar radiation so as to permit the rays of the sun to be directed into the tank directly or by reflection from reflecting surfaces 2I on the inner side of the half roof I9 and wall II) as shown. In this way the tank may be disposed in the yard near the building and the upper and lower coils in the tank may be connected by insulated piping in any suitable manner to the conditioning systern.

In Fig. 4 the piping connections between the upper coil I6 andthe main conditioning system are somewhat schematically shown and in which the coil is connected at one end to pipe 22 with a two-way valve 23 disposed at the junction of the pipe with the coil as shown. In the figure this pipe 22 extends entirely around the enclosed apparatus as shown. The other end of the coil I6 is connected to the right limb of a closed pipe 24. On the lower limb of the pipe 24 is a two-way valve 25 connected to pipe 26 leading to a compressor 21 driven by a motor 28. This compressor is connected by pipe 29 to the lower limb of pipe 22 as shown. A heat exchange element 30 is disposed between the left limb of pipe 24 and a two-way valve 3| disposed in the left limb of pipe 22. An expansion valve 32 is disposed between the upper limb of pipe 22 and a two-way valve 33 in the upper limb of pipe 24.

Considering Fig. 5, the lower coil I5 is shown connected at one end to a pipe 34 through a twoway valve 35. The pipe 34 extends entirely around the apparatus as shown. The other end of the coil I5 is connected to the right limb of a closed pipe 36. A two-way valve 31 is disposed in the lower limb of the pipe 36 and connects by pipe 38 to a compressor 39 which is driven by a motor 40. The compressor is connected also by pipe M to the lower limb of the pipe 34. The left hand limb of the pipe 36 is connected to an outdoor radiator or heat exchanger42, the other end of which is connected to a two-way valve 43 disposed in the left-hand limb of pipe 34. The upper limb of pipe 34 is connected to an expansion valve 44, the other side of which is connected to a two-way valve 45 disposed in the upper limb of pipe 36, 4

Referring to Fig. 4 with the four valves set as shown, and understanding that when they are moved, they are moved together by means to be later set forth, the circulation in the system will be from the right end of coil I6, through valve 23 through the lower limb of pipe 22, through pipe 23 and compressor 21, through pipe 26, valve .25, through left limb of pipe 24, through air-conditioning element 39, valve 3|, left-hand limb of pipe 22, upper limb of pipe 22, through expansion valve 32, right limb of pipe 24, to the other end of the coil I6.

If the valves are then moved for the reverse circulation, then the circulatory path will be as follows: From right end of coil I6, through valve 23, up through right limb of pipe 22, through upper limb of pipe 22, through the expansion valve 32, through left hand limb of pipe 2 t rou h the air-conditioning element 30, down through left-hand limb of pipe 22, through the lower limb of pipe 22, through pipe 29 to the compressor, through pipe 26, throug valve 25, through the right hand limb of pipe 24 to the other end of the coil I6.

Referring to Fig. 5, with the valves set as shown, the circulation will be as follows:

From right endof coil I5, through valve 35, down right limb of pipe 34, through lower limb of pipe 34, through pipe 4|, through the compressor 39, through pipe 38, through valve 31, through left limb of pipe 36. through the outside radiator element 42, through valve 43, up left limb of pipe 34, through the upper limb of pipe 34, through expansion valve 44, through valve 45, through right limb of pipe 36 to the other end of coil I5. Movement of the valves for reverse circulation will cause the following'path to be taken:

From right end of coil I5, up right limb of pipe 34, through upper limb of pipe 34, through expansion valve 44, through left limb of pipe 36, through the outside radiator element 42, through valve 43, down left limb of pipe 34, through lower limb of pipe 34, through pipe 4|, through compressor 39, through pipe 38, through valve 31, through right limb of pipe 36, to other end of coil I5 In Fig. 6 is shown a complete control circuit for a reverse cycle system where the lower coil is connected as shown in Fig. 5 to an outside radiating surface or the like. In this figure, when the main switch A is closed, it will be observed that two transformers 46 and 41 are disposed across the power lines 48 and 49. The secondary coil of transformer 41 is in series with a thermostat arm 50 which being disposed in tube I 5a is In thermal contact with the liquid in the reservoir and swings right and left as the temperature of the liquid goes up or down respectively. When it swings right, it contacts a wire 5| connected to coil 52 of a relay switch connected by wire 53 to another switch coil 54 which in turn is connected back to the other end of the secondary of transformer 41. When coil 52 is energized, switch arm 55 is pulled down, making contact from one side of power line over wire 56 with a wire 51 connected to one set of valve-operating coils 56 which are connected to the other side of the power line by wire 59. These coils 58 are in any suitable manner connected to move the valves shown in Fig. 5 in one direction, and another set 69 are similarly connected to throw the valves in the other direction. When coil 54 is energized as above, it pulls down switch arm 6| to make contact with the power line over wire 62 for the former 46 is connected the transformer 46. When with the power contact from one motor 40 oil the compressor which then starts up.

When the arm 58 of the tank thermostat swings to the left as the tank temperature drops it will ultimately contact with wire 88 connected to the arm 84 of another thermostat which is disposed in the walls of the building or the soil outside the tank, or at some other suitable point to be influenced by the seasonal outdoor temperature. Therefore, when the tank temperature has dropped sufilciently and the outside temperature has also dropped a predetermined amount, this second thermostat arm 84 will also close a circuit to wire 85 leading to coil which will then pull switch arm 85 upwardly and make contact with power to wire 61 to energize the valveoperating coils 80 and turn the valves to the reverse position and at the same time again over wire 58 cause the operation of the compressor as before. It will be seen that when'the tank temperature rises, the valves are operated and the compressor starts to work, but when the tank temperature drops beyond a definite amount, whether the valves are reversed and the compressor started depends not only on the tank temperature but also on the condition of the outside temperature as determined by the position of the thermostat arm 84.

Referring to the left side of Fig. 6, the transto an arm 88 of a thermostat which is disposed in the house itself and this arm swings right when the temperature rises,

and left when the temperature drops.

When the house temperature rises above a predetermined setting of the thermostat, arm 88 moves to the right and ultimately makes contact with wire 88 connected to coil 14. coil 14 is energized, switch arm 12 is pulled upwardly making contact from one side of the power line over wire 56 with a wire 18 connected to one set of valve-operating coils 10 which are connected to the other side of the power line by wire 58. These coils 10 are in any suitable manner connected to move the valves shown in Fig. 4 in one direction, and another set of coils 68 are connected to throw the valves in the other direction. The contact of arm 68 with wire 83 also energizes coil 80 by connecting it through the coil 14 and wire 8! to the secondary wiring of coil 88 is energized, switch arm 18 to make contact line through wire 19 to the motor 28 of the compressor, which then starts up. When the house temperature drops below a predetermined setting of the thermostat, arm 68 moves to the left and ultimately makes contact with wire 82 connected to coil 13. When coil 73 is energized, switch arm 12 is pulled down making side of the power line over wire 58 with a wire 15 connected to one set of valveoperating coils 69 which are connected to the other side of the power line by wire 58. These coils 68 are in any suitable manner connected to move the valves shown in Fig. 4 opposite to the movement caused by coils Ill. The contact of arm 68 with wire 82 also energizes coil 88 by connecting it through coil 18 and wire 8| to the secondary wiring of the transformer 46. When coil 88 is energized, it pulls down switch arm I8 to make contact with the power line through wire 18 to the motor 28 of the compressor, which then starts up.

With reference to Fig. 7, this diagram illustratesthe connections for the lower coil :5 when it is connected merely to a well or spring and this water is to be allowed to run through the coil it pulls down When at definite times. In this case, as is apparent, the two thermostats are the same as in the left half of Fig. 6 but the connections now cause the energization of the coil of a magnetic valve 1| to open the connection to the well or spring and allow water to run through coil [5, the other end of which in this case may be connected to a drain or any suitable outlet.

Having thus described in detail several preferred forms of the invention, some of the general problems before the engineer who has to design a reverse cycle refrigeration system for heating and cooling may be discussed in order to illustrate the utility of the invention. There are two main problems when the source of heat is outdoor air. The first one is that as the weather gets colder the demand for heat rises but the heat content of the outdoor air diminishes. The second one is that as soon as the outdoor temperature drops below freezing, ice gradually forms on the surface of the outdoor evaporating element; and of course ice reduces the efficiency of the evaporator. Because of these difiiculties, engineers always use ground water as a source of heat if it is available in sufiicient quantity at a high enough temperature. Here, again, there are several diiiiculties. First, warm ground water is not universally available in large enough quantities. Second, thereis the problem of disposing of the water after it has been cooled. An isolated plant could discharge its cooled water into the sewer, but if the reverse cycle systems were common, many plants could not thus dispose of waste water unless sewer systems were reconstructed. A third problem is the relatively low amount of heat available in a. gallon of ground water. Take water at 50 degrees F. and cool it to 33 degrees F. and only 17 B. t. u. are obtained per pound. However, take water which has been cooled to 32 degrees F. and continue to cool it until it freezes to ice at 32 degrees F. and B. t. u. per pound are liberated. Scientists and engineers have realized for many years that heating systems could be built to utilize the heat obtainable by freezing water if some way could be worked out for economical disposal of the ice thus formed.

My invention provides a means for utilizing the relatively large amount of heat obtainable by freezing water without having to dispose of the ice mechanically; provides means of heat storage which offers a large heat storage capacity at relatively low expense because no insulation against the escape of heat is required; and provides means for employing the heat storage capacity of .the soil or rock or groundwater in which the heat storage reservoir is built and by which it is partly surrounded. When the reverse cycle system is being used for heating, heat tends to be withdrawn both from the heat storage reservoir proper and from the surrounding medium. When the reverse cycle system is being used for cooling, heat tends to be absorbed by the water in the heat storage reservoir and by the surrounding material.

' It is apparent that the heating and cooling system above illustrated in the drawings is of the type in which the compressor and motor unit or units operate at about maximum capacity when they are in operation, the storage reservoir serving to smooth out the peaks of the demand for heating or cooling, as the case may be.

The main part of the invention is a tank designed to hold a suificient quantity of water in storage to meet, for a predetermined period of time, the heating or cooling demands of the system of which it is a part. Preferably this reservoir or tank will be constructed under the cellar of a house. In building a new house, for example, the excavation for the cellar will be made the required number of feet deeper, the tank will be constructed within the excavation and floored over except for a manhole. Thus, the cellar will have substantially the same appearance as a conventional cellar. However, the tank can easily be constructed under a house which has already been built. Also, the tank may be constructed elsewhere in some suitable spot adjacent the house. In regions where there is considerable winter sun, it may be desirable to build the tank in a location where considerable sun will fall upon it. Such a tank has been shown in Fig. 3 of the drawings. An outside location is feasible for the tank because it can be easily connected with the building to be conditioned by pipes run through insulated conduits in the ground. When the tank is constructed under a building it is not necessary to insulate it thermally because in heating, the water is frozen to remove the heat, hence it may be at any temperature Within the range at which it is liquid. It will tend to remain at the temperature of the surrounding soil. When the system is cooling the house rather than heating it, it is necessary only that the water in the tank be at a. temperature lower than the temperature of the compressed refrigerant, which temperature may be in the neighborhood of 100 degrees F. Therefore, no thermal insulation is necessary for the tank to carry out its function in weather when the system is cooling rather than heating the house. However, when the tank is built outside the building to take advantage of the sun's heating or for some other reason, it will be desirable to insulate the portions above ground and in the ground above the normal frost line in any suitable way that will reduce heat loss to the atmosphere. In a system designed for summer cooling as well as winter heating, curtains or doors adapted to reflect and retard the ingression of solar radiation and heat may be provided to cover the glass side of the tank roof structure in warm weather;

Another important feature of the tank constituting part of this invention is that it is connected with the surrounding soil or rock together with the ground water in said soil or rock by means of heat conductors. These conducting elements may be metal rods of suitable composition which are driven into the surrounding soil while the tank is under construction. In favorable soil formations these rods increase the heat capacity of the tank to a very substantial extent, hence a smaller tank than usual may be built and yet have the heat dissipating and absorbing capacity of a much larger tank without the rods.

A novel feature of the tank and its furnishings are the supports and conducting rods I8, which are made of metal or other material of good heatconducting qualities. Inaddition towholly or partly supporting the upper coil continuous heat conduction from the upper coil to the lower and vice versa and also distribute heat throughout the fluid contents of the tank, tending to counteract the tendency of undis-' turbed fluids to lie in layers, a warm layer over a substantially colder one.

Another advantage of the tank is that the liquid therein except for evaporation does not pass into or out of the tank during normal operation of the system. This condition makes it possible to stabilize the tank contents chemically l6, they provide in such ways as to retard the growth of bacteria and-the corrosion of the tubing and other fixtures in the tank.

Also under certain conditions, for example in a system installedlwhere true summer cooling load will be approximately equivalent to the winter heating load, the reservoir may be designed to freeze the soil surrounding it while the fluid within the tank remains in a liquid state. This result can be obtained by using in the tank a liquid substance with a freezing point below the freezing point of water, or by dissolving a suitable substance in water and using the solution in the tank. When enough heat is extracted from the tank liquid, heat will be conducted into the reservoir by the heat conducting elements that extend into the soil from the tank. Gradually as heat continues to be extracted from the soil, it will freeze. Then when the system, in response to changed weather conditions, reverses to operate as a cooling system, heat will pass outward from the tank into the soil and gradually thaw it. Auxiliary systems of heating and cooling the liquid in the tank,

described elsewhere in this specification, may be used. When the auxiliary system employs water, or waste fluids, as the source of heat, it is designed to discharge it before it has been cooled to the temperature coil.

where it would freeze in the It can be understood that in average installa-.

tions auxiliary heating or cooling of the tank contents will be necessary only in extremes of weather. The passage of heat along the heat; conducting rods from the surrounding soil into the tank will provide suflicient heat for mild weather conditions. The same is true when the system is cooling the building. The absorption of heat from the tank contents by the surrounding earth will be sufllcient except during periods of prolonged hot weather. However, one of the advantages of my tank is that it makes practical economical means of auxiliary heating during times of severe conditions.

- The simplest means of auxiliary heating is a coil disposed on or near the bottom of the tank, cneend of the coil being connected to a source of water under pressure and the other end being connected to a suitable'drain. No harm will be done in situations where water from a spring or artesian well is available at little or no expense by letting the water flow through this coil continually. That is to say, a continuous flow of water through the bottom coil fits in with the normal operation and function of the tank and its contents. The reason is that when the system is heating, the contents of the tank are normally only a little above the freezing point, and

along the upper coil iri the tank, are actually at the freezing point; and when the system is cooling, the contents of the tank may be at a temperature anywhere between the freezing point of water and a temperature a few degrees lower than the compressed refrigerant circulating in the upper coil l6. Where water must be pumped or purchased, ,a means of turning the pump on and off, or of opening and closing the valve leading to the supply main is provided as shown in Fig. 7.

In some installations, considerable auxiliary heat may be available in the sewage and other fluid wastes from the building. These wastes may be caused to flow through tubing submerged in the tank in such a way that they will give up a portion of their contained heat before they are discharged into the sewer. Where the temperature of the wastes remains at a. suitable low level in hot weather, they may be used as a cooling medium also. In situations where the waste temperature would be too high during the summer, a hand valve and a bypass are used to shunt the wastes around the tank in warm weather. Also, where the temperature of waste waters is likely to vary, and a sufllcient quantity of heating or cooling capacity is available to justify some expense in order to utilize it, automatic means of controlling the shunting may be installed. This means of affecting the tank temperature is not shown in the drawings, but the construction is obvious to anyone skilled in the art.

There will be a number of installations, especially when the system is installed in city dwellings, where sufficient auxiliary heating and cooling is not available, either in the form of inexpensive water or in the form of waste waters. In such situations, the outdoor air is used as a source of auxiliary heating and cooling. When the system is heating the building and therefore withdrawing heat from the tank contents, the tank thermostat controls the operation of an auxiliary reverse cycle refrigerator in such a way that when auxiliary heat is needed to keep the temperature of the tank contents above freezing, the auxiliary system goes into operation, removing heat from the outdoor air and adding it to'the contents of the tank. It is obvious that in a properly designed system, the auxiliary system can be made small in comparison to the size of the main reverse cycle system because the auxiliary system need not be designed to deliver a large amount of heat per hour but may instead be designed to deliver a relatively small amount per hour and operate over long periods of time when the weather is severe. Since the auxiliary system is relatively small, a proportionately larger outdoor heat radiator or exchanger surface may be used. When a large surface in relation to the capacity of the compressor may be used, there is less loss of efficiency due to ice formation. v

In general, a reverse cycle system designed for complete heating of a dwelling is more than large enough to take care of the cooling needs during hot weather because the difference in temperature levels in the winter is greater than in the summer. For the same reason, the tank and its contents will need less auxiliary cooling under average conditions than auxiliary heating. After a winter's operation, the tank, its contents, and the mass of soil adjacent to the heat-conducting rods will normally be at a temperature only a little above freezing. When the outdoor temperature makes it desirable to cool rather than to warm the building, the contents of the tank will then absorb heat from the main reverse cycle plant. This absorbed heat will pass out along the heat-conducting rods until the mass of matter surrounding the rods has reached a temperature level equal to the temperature of the tank contents. After this occurs, auxiliary cooling may be necessary, and it is provided by means of the bottom coil l5. Where cool water is available, it is circulated through the bottom coil. Where cool fluid wastes are available, they are passed through the bottom coil or through a third set of tubing that may be disposed in the tank. Where neither is available, an auxiliary reverse cycle refrigerator absorbs heat from the tank contents and dissipates it to the outdoor air. This latter action is controlled by thermostats and other automatic devices as mentioned above and as shown in the drawings.

It is obvious that when flowing water or waste fluids-are used to add or to subtract heat from the tank contents, the lower tank coil [6 may serve to conduct these liquids, but when outdoor air is used as a source and/or an absorber of heat, then coil 46 is either a condenser or an evaporator, depending on whether the reservoir is being heated or cooled, in a refrigeration system.

The general operation of a complete heating and cooling system is set forth and constructively described above with respect to the drawings. When the building interior falls below a predetermined temperature, the thermostatic element 68 swings to the-left and closes the contact to the indicated circuit whereby the motor 28 is started and the upper coils 69 are operated to throw the valves (see left side of Fig. 6). This valve circuit need be maintained for only a sumciently long period of time to place the valves in the desired position, which is the position for heating. a

The valves shown in Fig. 4 having thus been set for heating the dwelling, the compressor creates a partial vacuum in coil H3. The refrigerant then passes through the expansion valve 32 into the coil IS. The refrigerant, then absorbs heat through the walls of the coil I6, which heat comes from the water in the tank, especially the portion of it which is in contact with the coil l6 and the heat conducting supports H and I8. The gaseous refrigerant, having absorbed heat, is drawn through the compressor 21 where the compression raises the temperature to a suitable degree. From the compressor it passes through the heat exchanger 30 where by means of suitable fans, fins, or other suitable elements; depending upon the heat transfer system used to transfer heat to the air of the building, a portion of its heat is given up and it is cooled to a temperature at which it becomes a liquid.

The temperature of the evaporating refrigerant in the coil l6 causes the water in contact with the coil [6 and in contact with the support-- ing and heat conducting elements to freeze. However, this ice tends to thaw due to heat reaching it from the heat conducting supports l1 and. I8 and from the unfrozen water in the tank. During this process of thawing the ice lowers the temperature of the tank water, which is in contact with the tank thermostat 50, to a predetermined temperature-32 degrees F. in most installations but lower in plants designed to obtain heat by freezing the soil adjacent to the reservoir-the thermostatic element swings to the left and makes circuit through wire 63 with thermostat arm 64. This is another thermostat which is located in a suitable place in the building wall or in the soil. This thermostat is adapted to maintain a closed contact when swung to the left (shown in Fig. 6, right side) during the season when heat is normally required, but to open that contact during the season when cooling is required. Preferably it will be attached to the inner surface of an outer wall which has a moderate degree of heat conductivity and is not exposed to the sun. It can not be exposed directly to the outdoor air because it would then prevent the operation of the auxiliary tank heating system during abnormally warm winter weather, at which times, of course, the auxiliary heating system must nevertheless op- 11 erate if the temperature of the tank contents is below the predetermined level.

It is clear that if the contact is closed by thermostat arm 64 swinging to the left, then the closing of contact to wire 63 by arm 50 swinging to the left energizes the coils 54 and 66. As is obvious, the energization of these coils starts the motor 40 of the compressor 39 and operates the valves shown in Fig. to correctly position the valves in the auxiliary system so that heat is extracted from the outdoor air and transferred to the contents of the tank by means of the bottom coil [5, which, in this operation, acts as a condenser.

It is believed obvious from a study of the disclosure and the above description how opposite conditions will cause opposite effects in both the main system and the auxiliary system because of the operation of the thermostats described together with their attached electrical circuits. Heating of the tank during summer weather is prevented by the thermostat arm 64 not making its contact. Even if a prolonged spell of cool weather necessitates the use of the main system forheating, under average conditions, the amount of heat withdrawn from the tank and its surrounding mass will not be large enough to make heating of the tank necessary. Therefore the thermostat represented by the arm 64 is employed to prevent the operation of the auxiliary heating system during short spells of cool weather in the summer, electing instead to freeze a larger than usual proportion of the contents of the tank. This thermostat is preferably attached to the inner surface of the outer wall of the building; furthermore, its housing may be constructed of brick or other suitable material in such a way as to provide the right amount of lag behind dropping outdoor temperatures and the right amount of evening of fluctuations in outdoor temperatures. A similar lag could be obtained by the use of a timing element or mechanism in connection with the thermostat represented by the arm 50, or by burying the thermostat represented by the arm 64 in the soil surrounding the tank.

The elements that support the upper coil IS in the tank are constructed of heat conducting material. They may have conducting fins attached to increase their efliciency. Their purpose, in addition to supporting the upper tube system, is to tend to make the temperature throughout the tank uniform. It is and cold water will lie in layers in a tank if the water is not disturbed or caused to circulate. They will diffuse or mix slowly but the rate is much too slow for efficient functioning of the reservoir herein described. The heat conducting elements tend to distribute the heat evenly throughout the tank. Also, since they are attached to the lower coil l5, they also tend to conduct heat directly from it to the coil at the top of the tank; and in cooling theytend to conduct heat from the latter element directly into the lower coil.

While the invention. has been described in detail herein as to preferred forms thereof, it is to be' clearly understood that many changes and modifications may be made in the construction and operation without departing from the spirit and scope of the invention set forth, and it is not intended to limit the invention to the particular form shown but only in so far as it mav be limited by the scope of any one or more OI the appended claims.

well known that hot water 'and lower coil within said reservoir,

What I claim as my invention is:

1. In a heating system, a heat storage reservoir imbedded in the ground, coils in the upper and lower portions of said reservoir, separate reverse cycle refrigerating systems connected to the respective coils, a thermostat in one system adapted to control the circulation of refrigerant through the upper coil, and a differential thermostatic device in the other system controlling the flow of refrigerant in the lower coil and depending upon the difference in temperature between the reservoir liquid and the temperature at another point in the system.

2. In a heating system, a heat storage reservoir imbedded in the ground, coils in the upper and lower portions of said reservoir, heat conducting elements extending outwardly from the reservoir into the surrounding ground material, separate reverse cycle refrigerating systems connected to the respective coils, a thermostat in one system adapted to control the circulation of refrigerant through the upper coil, and a differential thermostatic device in the other system for controlling the flow of refrigerant in the lower coll depending upon the difference in temperance between the reservoir liquid and the temperature at another point in the system.

3. In a heating system, a closed heat storage reservoir imbedded in the ground and containing liquid sealed in said reservoir, heat conducting elements extending outwardly from the reservoir into the surrounding ground material, an upper separate reverse cycle refrigerating systems connected to the respective coils, a thermostat in one system adapted to control the direction of flow of refrigerant through the upper coil, and a differential thermostatic device in the other system for controlling the flow of refrigerant in the lower coil depending upon the difference in temperature between the reservoir liquid and the temperature at another point in the system.

. 4. In a heating and air conditioning system of the reverse cycle refrigeration type, a heat storage reservoir comprising a tank imbedded in the ground, liquid disposed in said tank, and heat conducting elements extending outwardly from the tank into the surrounding soil, in combination with a reverse cycle refrigeration system adapted to extract heat from the reservoir when the system is operating to heat and to dissipate heat into the reservoir when the system is operating to cool, and with a coil of tubing disposed near the bottom of the tank and designed to conduct flowing water or other suitable liquid through the tank in a heat exchange relationship, adding heat to the tank contents when their temperature is lower, and subtracting heat from the tank contents when their temperature is higher.

5. In an air conditioning system of the reverse cycle refrigeration type, a tank imbedded in the ground and containing brine or other suitable fluid having a freezing point lower than the freezing point of the surrounding soil, said brine or other fluid being disposed to circulate only within said tank, said tank being so disposed that when the system is operating to cool, heat will flow from the tank and its contents into the surrounding soil until the temperature of said soil is raised to the temperature of the tank and its contents, and when the system is operating to heat, heat will flow into the tank and its contents from the surrounding soil until the heat level of the tank and its contents is raised to the 13. temperature of the surrounding soil, a coil of tubing or other suitable heat exchange device disposed in the upper portion of the contents of said tank and forming part of a reverse cycle refrigeration system, dissipate heat into and extract heat from the said coil being disposed to tank and its contents, another coil of tubing or 3 ing point of the surrounding soil, said brine or other fluid being disposed to circulate only within said tank, said tank being so disposed that when the system is operating to cool, heat will flow from the tank and its contents into the surrounding soil until the temperature of said soil is raised to the temperature of the tank and its contents, and when the system is operating to heat, heat will flow into the tank and its contents from the surrounding soil until the heat level of the tank and its contents is raised to the temperature of the surrounding soil, a coil of tubing or other heat exchange device suitable for the condensing and evaporation of a refrigerant disposed in the contents of said tank and forming part of a reverse cycle refrigeration system, said coil being disposed to dissipate heat into and extract heat from the tank and its contents, another coil of tubing or other device suitable for the conduct of fluids, saidcoil being disposed in the contents of the tank and forming part of a simple heat exchange system whereby fluids flowing through said coil will dissipate heat into the tank and its contents or extract it therefrom according to the temperature gradients between the fluid flowing in the tube and the tank and its contents.

'7. In a heating and air conditioning system of the reverse cycle refrigeration type, a heat storage reservoir comprising a tank imbedded in the ground, liquid sealed in said tank, and heat conducting elements extending outwardly from the tank into the surrounding soil, in combination with a reverse cycle refrigeration system adapted to extract heat from the reservoir when the system is operating to heat and to dissipate heat into the reservoir when the system is operating to cool, and with a coil of tubing disposed near thebottom of the tank and designed to conduct flowing water or other suitable liquid through the tank in a heat exchange relationship, adding heat to the tank contents when their temperature is lower, and subtracting heat from the tank contents when their temperature is higher.

8. In a heating system of the reverse cycle refrigeration type, a heat storage reservoir imbedded in the ground, a pitched roof structure supported on said reservoir and containing in its sunward side a substance transparent to solar radiation, said roof structure being. adapted to trap -solar energy by transmitting and reflecting it into the tank contents, coils in the upper and lower portions of said reservoir, heat conducting elements extending outwardly from the reservoir into the surrounding ground material, separate reverse cycle refrigerating systems connected to the respective coils, a'thermostat in one system to be conditioned and adapted to control the circulation of refrigerant through the upper coil, and a differential thermostatic device in the other system adapted to control the flow of re frigerant in the lower coil depending upon the difference in temperature between the reservoir liquid and the temperature at another point in the system.

REGINALD R. HAWKINS.

REFERENCES orrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS 

